MMR is clinically referred to as drug rash, and typically presents as bright red papules, purplish-red macules, asymmetric round edematous red plaques, as well as large blisters, subcutaneous petechiae, and other lesion states. Drug rashes are a form of adverse drug reaction and are collectively referred to as adverse drug reactions. Drug rashes are usually caused by inflammatory damage to the skin and mucous membranes of the body after the drug enters the body through various ways, such as oral intake or injection and inhalation, and are usually manifested as various skin lesions, but in severe cases, they may also involve other systems of the body. Generally speaking, 6 to 12 days after the MMR vaccination, scattered skin rashes may appear, mostly manifested as red papules, patches, and windmills, etc., and the time of appearance of the rashes is usually less than 2 days, which usually do not need special treatment, if the rashes are serious or do not subside for a long time, they should be dealt with in hospitals in a timely manner, so as to avoid delaying the condition.